Manufacture of textile and other materials



Patented Jams, 1939 UNITED, STATE MANUFACTURE or TEXTILE ANno'rnEa o MATERIALS w I Henry Dreyfus, London, and Robert Wighton j Moncriefi and Frank Brentnall Hill, Spondon,

near Derby, England, assignors to Celane'se Corporation of America, a corporation ofDelaware I No Drawing. Application November 12, 1936, Se-

rial No. 110,472. In Great Britain November s PATENT OFFICE the treatment of continuous filaments of cellulose acetate and of threads consisting of said filaments which comprises'stretchingthe filaments or threads in the presence of saturated. or I wet steam under pressure at a temperature above 100 C. The temperature of the steam may, for example, be 110, 120 or- 130 C. or more, 'the pressure being appropriate to maintain the steam in the saturated or wet condition, for example a pressure of 10, 20, 30 pounds or more per square inch above atmospheric pressure. As is indicated in the said specification,- by this meansstretches of many hundreds per cent may be obtained.

In U. S. application S. No; 69,282 filed March 17, 1936, an apparatus is described in which there is provided in front of the steam stretching chamber a chamber which contains compressed air and which contains the feed device for the filaments or threads. In passing through this apparatus the'threads'first'pass from the open air 0 into the compressed air" chamber by means of suitable orifices, then pass in substantially nonslipping contact'with nip rollers or other feed device located in the compressed air chamber, pass from the compressed air chamber through suitable orifices into the steam chamber, steam being projected on to the threads immediately upon their entry into'the steam chamber, and

then the threads pass out of the steam chamberinto the open air through suitable orifices, and 40 are taken through nip rollers or in contact with other suitable stretching device. The tension exerted by the steam upon the threads in traversing the inlet orifices to the pressure steam chamber is reduced, and by suitably adjusting the v pressure of the compressed air to that'of the steam, may be substantially eliminated. As is explained in the said specification, it is desirable to maintain a slightly higher pressure in the steam chamber than in the compressed air chamber,

say a pressure higher by about /5 pound per square inch, so as to avoid passage of the air into the steam chamber. .Bymeans oi the processand. apparatus of the above specifications stretches of 1000% or more may be obtained. 5 We have'now found that the stretch obtainable contemplated by the present invention it is de- 8 Claims. (ore-132 may be still further increased by increasing the temperature of the steam. We have found, for example, that it is possible to 'obtain stretches of 50, 100, 150 and 200 times or more the original length of the filaments and threads. Thus, at a 5 steam temperature of v 138 C. and the appropriate conditions to maintain the steam just'wet, a stretch of about 50 times may be obtained using the ordinary commercial acetone-soluble cellulose acetate artificial silk filaments and threads; 10

For higher stretches, such as 100, 150 and 200 times, the temperature may be still further increased, for example to 140 or 0., and .the pressure increased appropriately.

It is ind'cated in'the above specifications that 5 I the stretch many hundreds per cent may be obtained wit a length of stretching run in the steam of only a few inches, but that it is preferable to exten the length of the steam chamber to some feet, for example 3-6 feet or more, the g precise length depending upon ,the temperature and the amount and rate of stretching. It is found that with the increased degrees of stretch sirable, in order to obtain the best results, to decrease the length of the steam path. For example, in stretching 50 times,-a very suitable length of steam chamber is 18 inches, and in stretching 100 and times, the chamber, may be still further reduced to about 9 inches. 30

For starting up in running these increased degrees of stretch, it is found to be preferable to start up by threading the threads through the steaming apparatus with no steam, to fix the end plates in position, and to turn the steam on 35 t and to increase its pressure until it is suitable for running a stretch of comparatively low degree, such as*10 times, and when the stretching is'running in a stable condition, the threadsv being drawn-through bythe stretching rollers at .the

requiredrate, to. increase the steam pressure and the stretch simultaneously until the desired degree of stretch is reached.

As indicated in U. S. application-,8. No. 123,104, 45

the best temperature at which towork depends upon a large number of factors, and reference is made to this specification for these factors, and

also for other details of the process;

have an increased tensile strengthas compared with materials which have been stretched to lower degrees, but to have an extensibility which is not;

substantially decreased as compared with mate- 5;

rials which have undergone the lower degrees of stretch. They may even have an extensibility somewhat greater than that of the materials stretched to a lower degree.

'In addition to obtaining high tenacity, the process may result in the production of materials of very fine denier, the actual denier depending, of course, upon the initial denier of the materials and upon the degree of stretch. As in U. S. application S. No. 123,104, the starting material may be filaments each having a denier of 2 or up'to 10, 20 or more With the present high degrees of stretch it is desirable to begin with filaments of comparatively high denier.

In U. S. application S. No. 123,104, the stretching treatment is extended to spun yarns of cellulose acetate and other materials, for example ribbons, films, foils and the like of cellulose acetate and also to filaments, threads, spun yarns, ribbons, foils, films and the like of cellulose esters and ethers other than acetate. vention also includes the application of the conditions necessary to produce the higher degrees of stretch above contemplated to the above materials.

In U. S. application S. No. 121,150 filed January 18, 1937, processes are described in which the above materials are subjected to a stretching operation in presence of hot water, preferably under pressure, the temperature and pressure conditions being, for example, similar to those employed when using steam. Similarly in thisprocess, by increasing the temperature of the water to 138 C. and above, for example 140 to 145 C., and employing the appropriate pressure to maintain the water in the liquid state, much higher degrees of stretch are obtainable, and the present invention includes the use of hot water under these conditions. I

Improved results may be obtained by causing the hot water to flow in the same direction as that of the travel of the materials, thus reducing or eliminating the drag exerted on the materials by the water.

The following examples illustrate the invention:

Example 1 Cellulose acetate yarn is stretched by means of an apparatus comprising an end chamber and a steam stretching chamber as illustrated in U. S. application S. No. 69,282 filed March 17, 1936, the steam chamber being about 18 inches in length and containing wet steam at a. temperature of 142 C. The end chamber contains air at a pressure of about A: to 1 pound per square inch lower than the pressure of the steam and the yarn is stretched to about 90 times its original length. Products having a very high tenacity may thus be obtained.

Example 2 is about 9 inches in length. The chamber con-v tains wet steam at a temperature of 144 C. and

the yarn is stretched to about 170 times its original length. Similar products to those of Example 1 may be obtained.

Example 3 Cellulose acetate yarn is stretched in hot water in an apparatus similar to that described and illustrated in U. S. application S. No. 47,798 filed November 1, 1935. The temperature of the water The present inis about 150 C. and the length of the hot water chamber is about 9 inches. The yarn is stretched to 60 to 80 times its original length, and yarn of greatly increased tenacity may thus be obtained.

The stretched materials may be subjected to any desired after-treatment processes. Thus, the stretched materials may be treated with shrinking agents to modify their properties, and particularly to improve their extensibility. Suitable processes for this purpose are described in U. S'Patent No. 2,058,422. In particular reference is made to the latent solvents referred to in that specification, for example a mixture of methylene chloride and benzene.

Again, the stretched materials may be subjected to proceses of saponification. The saponification may be suchas to lead to a relatively small loss in weight, for example suflicient to give the materials an affinity for cotton dyestuffs, or. may be complete or substantially complete, i. e., so as to eliminate all or substantially all of the acetyl content. The saponification may be effected under such conditions of tension that shrinkage takes place during or immediately after the saponification, this being advantageous from the point of view of the extensibility of the products.

Such further treatments may be carried out as operations separate from the stretching or may be carried out continuously with stretching. Thus, for example, the invention includes a continuous operation which involves first stretching and then shrinking; a continuous operation involving stretching followed by saponification; and a continuous operation involving stretching, shrinking, and finally saponification.

The term aqueous fiuid as employed in the claims is to be understood as meaning only fluids which contain particles of water in the liquid state.

Having now described our invention, what we desire to secure by Letters Patent is:

1. Process for improving the strength of filaments, foils and similar materials of organic derivatives of cellulose, which comprises stretching the materials to at least 50 times their original length in an aqueous fluid at a temperature of at least 138 C., the length of the path of the materials through the aqueous fluid not exceeding 18 inches;

2. Process for improving the strength of filaments, foils and similar materials of cellulose acetate, which comprises stretching the materials to at least 50 times their original length in an aqueous fluid at a temperature of at least 138 C., the length of the path of the materials through the aqueous fluid not exceeding 18 inches.

3. Process for improving the strength of filaments, threads and similar materials of cellulose acetate,which comprises stretching the materials to at least 50 times their original length in wet steam at a temperature of 140 C., the length of the path of the materials through the steam not exceeding 18 inches.

4. Process'for improving the strength of filaments, foils and similar materials of organic derivatives of cellulose, which comprises passing the materials through an end pressure chamber containing an inert fluid under pressure, from said chamber into a stretching chamber not exceeding 18 inches in length and containing wet steam at a temperature of at least 138 C., the pressure of the inert fluid being lower, but only slightly lower, than that of the steam so that tension on the materials due to flow of steam through the orifices for the entry of the materials into the stretching chamber is substantially eliminated, and stretching the materials to at least times their original length during their travel through the steam.

5. Process for improving the strength of filaments, foils and similar materials of organic derivatives of cellulose, which comprises passing the materialsthrough an end pressure chamber containing an inert fluid under pressure, from said chamber into a stretching chamber not exceeding 18 inches in length and containing hot water at a temperature of at least 138 C., the pressure of the inert fluid being lower, but only slightly lower, than that of the hot water so that tension on the materials due to flow of hot water through the orifices for the entry of the materials into the stretching chamber is substantially eliminated, and stretching the materials to at least 50 times their original length during their travel through the hot water.

6. Process forimproving the strength of fllaments, threads and similar materials of cellulose acetate, which comprises passing the materials through an end pressure chamber containing an inert fluid under pressure, from said chamber into a stretching chamber not exceeding 18 inches in length and containing wet steam at a tempera-.

ture of at least 138 C., the pressure of the inert fluid being lower, but only slightly lower, than that of the steam so that tension on the materials due to flow of steam through the orifices for the entry of the materials into thestretching 'chamher is substantially eliminated, and stretching the materials to at least times their original length during their travel through the steam.

7. Process for improving the strength of filaments, threads and similar materials of cellulose acetate, which comprises passing the materials through an end pressure chamber containing an inert fluid under pressure, from said chamber into a stretching chamber not exceeding 18 inches in length and containing wet steam at a tempera- ,ture of at least C., the pressure of the inert fluid being lower, but only slightly lower, than that of the steam so that tension on the mate-. rials due to flow of steam through the orifices for the entry of the materials into the stretching chamber is substantially eliminated, and stretching the materials to at least 100 times their original length during their travel through the steam.

8. Process for improving the strength of filaments, threads and similar materials of cellulose acetate, which comprises passing the materialsv through an end pressure chamber containing an inert fluid under :pressure, from said chamber into a stretching chamber not exceeding 18 inches in length-and containing hot water at a temperature of at least 138 C., the pressure of the inert fluid being lower, but only slightly lower, than that of the hot water so that tension on the materials due to flow of hot water through the orifices for the entryof the materials into the stretching chamber is substantially eliminated, and stretching the materials to atleast 50 times their original length during their travel through the hot water.

- HENRY DREYFUS.

ROBERT WIGHTON MONCRIEFF. FRANK BREN'I'NAIL HILL. 

